package com.wuxiaoqin.uitls.util;


import org.apache.commons.codec.binary.Base64;
import org.apache.commons.io.IOUtils;

import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

//import org.apache.commons.codec.binary.Base64;

public class RSAUtils {

    public static final String CHARSET = "UTF-8";
    public static final String RSA_ALGORITHM = "RSA";


    //创建公钥和秘钥
    public static Map<String, String> createKeys(int keySize){
        //为RSA算法创建一个KeyPairGenerator对象
        KeyPairGenerator kpg;
        try{
            kpg = KeyPairGenerator.getInstance(RSA_ALGORITHM);
        }catch(NoSuchAlgorithmException e){
            throw new IllegalArgumentException("No such algorithm-->[" + RSA_ALGORITHM + "]");
        }

        //初始化KeyPairGenerator对象,密钥长度
        kpg.initialize(keySize);
        //生成密匙对
        KeyPair keyPair = kpg.generateKeyPair();
        //得到公钥
        Key publicKey = keyPair.getPublic();
        String publicKeyStr = Base64.encodeBase64URLSafeString(publicKey.getEncoded());
        //得到私钥
        Key privateKey = keyPair.getPrivate();
        String privateKeyStr = Base64.encodeBase64URLSafeString(privateKey.getEncoded());
        Map<String, String> keyPairMap = new HashMap<String, String>();
        keyPairMap.put("publicKey", publicKeyStr);
        keyPairMap.put("privateKey", privateKeyStr);

        return keyPairMap;
    }

    /**
     * 得到公钥
     * @param publicKey 密钥字符串（经过base64编码）
     * @throws Exception
     */
    public static RSAPublicKey getPublicKey(String publicKey) throws NoSuchAlgorithmException, InvalidKeySpecException {
        //通过X509编码的Key指令获得公钥对象
        KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(Base64.decodeBase64(publicKey));
        RSAPublicKey key = (RSAPublicKey) keyFactory.generatePublic(x509KeySpec);
        return key;
    }

    /**
     * 得到私钥
     * @param privateKey 密钥字符串（经过base64编码）
     * @throws Exception
     */
    public static RSAPrivateKey getPrivateKey(String privateKey) throws NoSuchAlgorithmException, InvalidKeySpecException {
        //通过PKCS#8编码的Key指令获得私钥对象
        KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKey));
        RSAPrivateKey key = (RSAPrivateKey) keyFactory.generatePrivate(pkcs8KeySpec);
        return key;
    }

    /**
     * 公钥加密
     * @param data
     * @param publicKey
     * @return
     */
    public static String publicEncrypt(String data, RSAPublicKey publicKey){
        try{
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            return Base64.encodeBase64URLSafeString(rsaSplitCodec(cipher, Cipher.ENCRYPT_MODE, data.getBytes(CHARSET), publicKey.getModulus().bitLength()));
        }catch(Exception e){
            throw new RuntimeException("加密字符串[" + data + "]时遇到异常", e);
        }
    }

    /**
     * 私钥解密
     * @param data
     * @param privateKey
     * @return
     */

    public static String privateDecrypt(String data, RSAPrivateKey privateKey){
        //java.security.Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
        try{
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            return new String(rsaSplitCodec(cipher, Cipher.DECRYPT_MODE, Base64.decodeBase64(data), privateKey.getModulus().bitLength()), CHARSET);
        }catch(Exception e){
            throw new RuntimeException("解密字符串[" + data + "]时遇到异常", e);
        }
    }

    /**
     * 私钥加密
     * @param data
     * @param privateKey
     * @return
     */

    public static String privateEncrypt(String data, RSAPrivateKey privateKey){
        try{
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.ENCRYPT_MODE, privateKey);
            return Base64.encodeBase64URLSafeString(rsaSplitCodec(cipher, Cipher.ENCRYPT_MODE, data.getBytes(CHARSET), privateKey.getModulus().bitLength()));
        }catch(Exception e){
            throw new RuntimeException("加密字符串[" + data + "]时遇到异常", e);
        }
    }

    /**
     * 公钥解密
     * @param data
     * @param publicKey
     * @return
     */
    public static String publicDecrypt(String data, RSAPublicKey publicKey){
        try{
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.DECRYPT_MODE, publicKey);
            return new String(rsaSplitCodec(cipher, Cipher.DECRYPT_MODE, Base64.decodeBase64(data), publicKey.getModulus().bitLength()), CHARSET);
        }catch(Exception e){
            throw new RuntimeException("解密字符串[" + data + "]时遇到异常", e);
        }
    }



    private static byte[] rsaSplitCodec(Cipher cipher, int opmode, byte[] datas, int keySize){
        int maxBlock = 0;
        if(opmode == Cipher.DECRYPT_MODE){
            maxBlock = keySize / 8;
        }else{
            maxBlock = keySize / 8 - 11;
        }
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] buff;
        int i = 0;
        try{
            while(datas.length > offSet){
                if(datas.length-offSet > maxBlock){
                    buff = cipher.doFinal(datas, offSet, maxBlock);
                }else{
                    buff = cipher.doFinal(datas, offSet, datas.length-offSet);
                }
                out.write(buff, 0, buff.length);
                i++;
                offSet = i * maxBlock;
            }
        }catch(Exception e){
            throw new RuntimeException("加解密阀值为["+maxBlock+"]的数据时发生异常", e);
        }
        byte[] resultDatas = out.toByteArray();
        IOUtils.closeQuietly(out);
        return resultDatas;
    }

    public static void main (String[] args) throws Exception {
        Map<String, String> keyMap = com.wuxiaoqin.uitls.util.RSAUtils.createKeys(512);
        //公钥
        String  publicKey = keyMap.get("publicKey");
        //私钥
        String  privateKey = keyMap.get("privateKey");
        //String str = "2000918131X";
        String str = "123456";
        System.out.println("\r明文：\r\n" + str);
        System.out.println("\r私钥：\r\n" + privateKey);
        System.out.println("\r明文大小：\r\n" + str.getBytes().length);

        //公钥加密   需要明文密码和公钥 用户传过来的就是明文
        String encodedData = com.wuxiaoqin.uitls.util.RSAUtils.
                publicEncrypt(str, com.wuxiaoqin.uitls.util.RSAUtils.getPublicKey(publicKey));
        System.out.println("密文：\r\n" + encodedData);


/*        //私钥解密 需要密文 和 私钥    数据库拿到的就是密文
        String decodedData = com.wuxiaoqin.uitls.util.RSAUtils.
                privateDecrypt(encodedData, com.wuxiaoqin.uitls.util.RSAUtils.getPrivateKey(privateKey));
        System.out.println("解密后文字: \r\n" + decodedData);

        privateKey="MIIBVQIBADANBgkqhkiG9w0BAQEFAASCAT8wggE7AgEAAkEAj9PhlOvK5EwgT72qz_eSedhz9q0eU67Ql0NLTnD5xQKwGxKgbgHQRk1NyLy9za-l27fMn_hMkuLtDA3-QGAHtQIDAQABAkBfvMIjxvC_Fo1Lhwz0ce9me9Z1FLdjLLJcfcba6AjaQfhPKpgGZmShMqNQvAXwenqGruUIa5o2tpIeHD7mPNIBAiEAweVTUbEiTRzXVL0ll4HJLKZ1v-uyBnP74aEd4VvNriUCIQC95St6NFyPduFQNJQnHXe1bwp9bVWcKQnTwiylBgXWUQIhAK0PwelVYBdR2cRxut7a4bOvs8OkXNazqSs_QktGRHPdAiA_EI3Y3uzihGOdpGiTePjZm5ALSbVF0GdAGVuETrS_kQIhALVHuEtJ5AGZcSX2BEyEPz2Ee5u2Di7guYc9fRvnQR7-";

        String decodedData1 = com.wuxiaoqin.uitls.util.RSAUtils.
                privateDecrypt("aexsbRoT5p3a10st6ozwyP7pRzg_DCAsEfvq4RFvuwf_2zCZFUdMk-zkbKusTJppO8idX8gloLo0ib1yomv4SQ", com.wuxiaoqin.uitls.util.RSAUtils.getPrivateKey(privateKey));
        System.out.println("解密后文字: \r\n" + decodedData1);*/
    }
}
